PHOTOINDUCED OPTICAL ANISOTROPY AND COLOR ADAPTATION IN SILVER-CONTAINING GLASSES

This paper reports photoinduced optical anisotropy (dichromism and birefringence) and color adaptation in oxide glasses containing silver and halogens. The effects are found in both photochromic and fixed-tint glasses. In certain of the photochromic glasses there is memory, such that after thermal fading redarkening by uv radiation reestablishes the anisotropic or color-adapted state. Dichroic ratios of 4 and birefringences of Δn=10 -4 have been measured. The effects, similar to the Herschel and Weigert effects in silver halide photography, are explained on the basis of optical bleaching of anisotropically shaped submicroscopic aggregates of silver in contact with a silver halide.